Heat filter device



April 1936. FfL. SHAHAN HEAT FILTER DEVICE Filed Feb. 10, 1954 2 Sheets-Sheet l lNVE/VTOR FRANK L. SHAHAN Y Q/M A T TORNE'V April 28,1936. F, H H 2,038,765

HEAT FILTER DEVICE Filed Feb. 10, 1934 2 Sheets-Sheet 2 N VE N 70/? FRANK L. SHAH/4N AT TORNEV Patented Apr. 28, 1936 UNITED STATES PATENT OFFICE HEAT FILTER DEVICE Frank L. Shahan, Phoenix, Ariz.

Application February 10, 1934, Serial No. 710,759 6 Claims. (Cl. 122-27) It is a well known fact that large quantities of heat energy are thrown away in the slag clumps of all kinds of smelters.

My invention relates to heat-filter devices for the utilization of the heat contained in this slag, or from other molten waste material drawn off from other types of furnaces; and has for its objects, first to provide a receptacle into which the molten slag may be poured and in which it may be allowed to cool; second, to provide a means for absorbing the heat from the slag at a comparatively uniform rate and of applying said heat to water, or other similar substance, for the production of steam or the like; third, to provide a boiler adapted to receive said heat, and generate steam, and deliver it to steam operated machinery; and fourth, to provide a means for the efficient removal of the slag after it has cooled and solidified. Other objects will appear hereinafter.

The term heat-filter, as used herein, means apparatus, including a substance, which is a semi-insulator, the texture and composition being such as to permit heat to pass thru it at a comparatively uniform rate. The term also contemplates a device adapted to hold heat in check and permit it to escape into a cooler portion of the device where it may be made to perform work, at a comparatively uniform rate which may be determined by the semi-insulator used and the arrangement of the parts of the apparatus.

I attain these objects by the mechanism, devices and structures illustrated in the accom panying drawings in which- I Figure 1 is a side elevation in semi-section of the entire device; Figure 2, a section taken along line 2--2, Fig. 1; Figure'3, a partial horizontal section taken along line 3-3, Fig. 1.

Since the side elevational construction of my half of it is shown in section in Figure 1, and therefore the right half of the figure shows the outward aspect of the device as viewed from the front. Hence, where numerals indicate a part shown on one side only, it may be understood, according to the context, that it has a substan tially similar counterpart on the opposite side.

In general, the principal parts of my device are a central slag mould chamber 2, a water tube boiler 3, the legs of which straddle the slag mould chamber, a heat filter 4, and a slag removal device consisting principally of a truck 5.

The slag mould chamber is located in the central portion of the device, has the shape of a frustum of a pyramid; and is bounded by indevice is substantially symmetrical only the left wardly inclined side plates 6, the inner walls of doors 8 and 9, at the front and back respectively, and by plate 1 at the bottom. These parts are preferably made of heavy cast iron of the same type as is commonly used for slag pots.

The top of this chamber is closed by a sheet iron roof [0 which holds asbestos insulation material H in place against a heavy cast iron top plate l2.

The boiler 3 consists of an upper steam drum I3, bottom headers [4 connected by banks of circulating tubes l5 and I6. These two banks of tubes and the bottom header comprise. the two legs of the boiler and extend downward along and parallel to the side plates 6 on each side of the mould chamber (thus in efiect straddling it). The tubes l5, nearest the side plates, I term the hot tubes. They are at least four inches in diameter and spaced about the same distance apart, and are positioned approximately the same distance from walls 6.

The tubes I6 are more numerous and are spaced closer together (see Fig. 3) in order to provide adequate circulation as indicated by arrows 30 with slower descending than ascending currents and to avoid the possibility of the formation of steam pockets which might cause back pressure.

In order to allow for expansion and contraction of tubes [5 they are set into the bottom plate of steam drum l3 through circular corrugations ll.

Support is afforded the stem drum by resting in part in the top plate l2, and in part on the outer supporting plates I8. The bottom headers are supported on brackets l9 resting on founda tions 26 which also support plates 6 and l8.

The boiler is provided with the usual accessories such as the steam dome 2|, delivery pipe 22, baffle plate 23, steam gauge 24, water gauge 25, safety valve 26, blow off pipe 21, and mud manhole 28. It is also to be understood that the usual stay bolts and pressure plates may be included in the interior construction of the boiler depending on the pressure to be used, but for the purpose of clearness these are not shown in thedrawings.

The heat filter 4 may be described as composed of the side walls 6 and I8 with the heat filter substance 29 contained therebetween, and surrounding the banks of tubes l5 and Hi. It is the function of the heat filter to not only act as a conductor and distributor of the heat from the slag mould chamber but also to act as a reservoir for the heat during the removal of the slag ingot, and

- the introduction of a fresh charge. The extreme difference in temperature between the fresh slag and average boiler water temperature is 1600 deg. F. The heat filter substance must, therefore be a fair insulator and have the capacity to absorb and store heat to a certain extent. It must be uniform in texture, and not deteriorate or cake at the working temperatures, and must be pliant enough to allow for the expansion and contraction of thecontacting and surrounding surfaces. After numerous experiments I have found that baked clay (dehydrated) finely ground and sifted free 7 would beless with slag from copper smelters than when slag fromiron furnacesis used. In all instances, however, the distance between tube banks I 5 and I6 is such that tubes I6 receive practically no heat by either radiation or conduction from plates 6. In fact, the heat they maintain comes from the water circulating through them and the substance surrounding them acts as an insulator rather than a conductorof heat.

' When a fresh'charge of slag is introduced heat filters. (by conduction and radiation) from plate 6 'thru the layer of heat filter substance nearest the plate to the first bank of tubes I5. Water circulating thru these tubes absorbs the heat practically as fast as it reaches the tube surfaces. Heat penetrating by conduction passes on past this first bank of tubes and permeates the heat filter substance-between tube'banks I5 and I6. The volume of this substance is great enough so that considerable heat is stored but the nature of thesubstance 'is such that theportion surrounding tubes I6 never reaches a temperature greater than the water circulating downward thru these tubes. The distance between the tube banks should be approximately four times that between plate 6 and tube bank I5.

The edges of the bottom plate! areprovided with a rim 3| beveled to fit tightly against the walls of plates 6, as well as the inner faces of doors 8 and 9, when the plate is raised into the these two plates. other suitable similar material.

position indicated in Fig. 1. This plate is supported on and attached to the tilting bed 32 of truck 5 and insulating material 33 spaced between This may consist of firebrick or The tilting bed 32 is supported on truck 5 by bearings 34, and

v a suggested means of tilting the bed is indicated by the worm gear system 25 operated by hand wheel 36. The truckis raised into position by a movable frame having four vertical notched supports 21 adapted to fit under the truck axle housings. The weight of 'the truck and frame is counterbalanced byweight 38 through lever system 29, and the position of the weight governed by steam pressure operating on piston 4!] controlled by valves 48 feeding through pipe 49 or by other suitable means.

7 It is to be understood that the portion of the 7 drawing showing the truck balancing and lifting mechanism is semi-diagrammatic in character I and not drawn to scale relative to the other parts of the structure. V The entire outer surface of the deviceis covered with insulating material ll and this, in turn, is covered with, and held in place, by

. sheathing 42.

It will be noted by reference to Fig. 3 that the doors 8 and 9 are divided into two halves, each hinged to the respective edges of plates 6 so that they open by swinging outward. The outside of the heavy door plates is covered with insulating material 4| and this is. held in place by metal sheathing 42 similar to the covering over the rest of the device. V

The doors are proportioned so that they over lap all parts of the jam contact surfaces by at least two inches, and the hinges 43 are propore tioned and pinioned so that the doors swing out- All seams between the several parts of the slag w mould chamber are thus made as nearly tight as the nature of the structure will permit, and it is to be understood that all are atleast two inches thick. Consequently, leakage of molten slag is reduced to a minimum since it chills quickly in a deep crevice and forms a plug which stops leakage. 7 7

In operation, water is introduced into the boiler in'the usual manner. Slag is then run into chamber 2 to about the level indicated at 46, Fig. 2. After it has cooled, solidified, and reached a temperature slightly above that necessary to maintain steampressure, the bars on the doors are removed, the doors opened and truck 5 carrying the slag ingot lowered onto track rails 41. Due to the slant of walls 6 the weight of the ingot overcomes any tendency toward cleavage. 1 After the introduction of the molten slag the heat which it contains isabsorbed principally by the plates Ii. After permeating these, it travels through the substance 29 until it strikestubes I5 where most of it is absorbed. Due to the nature of this substance the heat is allowed to filter from the slag to the boiler Water at a comparative uniform rate. Some heat will ascend and permeate the top insulation I I and thence find its way directly into steam drum I3 through its bottom, but the major part of the energy is absorbed into the water in tubes I5 7 V Having now described my invention and its us I claim:

1. A heat-filter device for the recovery and' movable bottom plate adapted to remove moulded slag therefrom, a water tube boiler the legs of which straddle said slag mould chamber, and the steam drum positioned thereabove and-a heat filter composed of a semi-insulating substance intermediate the side walls of saiol's lag mould chamber and the legs of said boiler whereby heat is permitted to pass at a predetermined rate from slag within said chamber to the water in the circulating tubes of said boiler.

2. A device of the kind described comprising, in combination, a slag mould chamber having the shape of a truncated pyramid and provided with hinged end walls and a removable bottom plate, a steam water tube boiler positioned above said chamber with its water legs extending downward chamber and spaced therefrom, a heat filter, consisting of powdered clay, filling the space between the side walls of said mould chamber and the tubes of said boiler, and heat insulating material surrounding the outer surfaces of the entire device. I

3. A device for the recovery of heat from slag and the conversion thereof to the production of steam, comprising, in combination, a slag mould chamber provided with spouts for the introduction of slag and having means for the removal of the slag ingot, a steam boiler contiguous to said slag mould chamber but thermally separated therefrom by a heat filter, and a heat filter thermally intermediate said slag mould chamber and said boiler composed of finely ground dehydrated clay loosely packed between the slag mould chamber and the steam producing members of said boiler.

4. A device for the recovery of heat from slag and the conversion thereof to the production of steam comprising, in combination, a slag mould chamber provided with spouts for the introduction of molten slag and having means for the removal of the slag ingot, and having walls adjacent the steam producing members of a steam boiler, a steam boiler contiguous to said slag mould chamber and adapted to receive heat therefrom but thermally separated therefrom by a heat filter having its steam production surfaces adjacent the walls of said slag mould chamber, and a heat filter thermally intermediate said slag mould chamber and said boiler composed of finely ground dehydrated clay loosely packed between the slag mould chamber and the steam producing members of said boiler.

5. A device for the recovery of heat from slag and the conversion thereof into steam comprising, in combination, a slag mould chamber having means for the introduction and removal of slag, a boiler contiguous thereto, and a heat filter intermediate said slag mould chamber andsaid boiler composed of finely divided dehydrated powdered clay, adapted to permit the heat contained in said slag to pass into said boiler at a predetermined rate.

6. A device for the recovery of heat from slag and the conversion thereof into steam comprising, in combination, a slag mould chamber having means for the introduction and removal of slag, and upwardly extending side walls, a water tube boiler contiguous thereto having an inner and an outer bank of circulation tubes connecting at the top to a steam drum and at the bottom to a header, an insulated outer casing surrounding said entire boiler, a heat filter substance intermediate the side walls of said slag mould chamber and the outer casing of said boiler composed of finely divided dehydrated clay, the circulation tubes of said boiler being positioned intermediate said side walls of said slag mould chamber and said boiler casing and within said tubes being positioned a distance therefrom so 9 that they do not receive heat enough to generate steam therewithin.

FRANK L. SHAHAN. 

